Thermoplastic halopolymer composition

ABSTRACT

The invention pertains to a thermoplastic fluoropolymer composition comprising: at least one thermoplastic partially fluorinated fluoropolymer having a melt flow index (MFI) of less than 10 g/10 min, as measured according to ASTM D-1238 under a piston load of 5 kg polymer A; from 0.05 to 5% by weight of A at least one (per)fluoropolyether, polymer B; and from 0 to 10% by weight of A of at least one per(halo)fluoropolymer polymer C. The addition of a (per)fluoropolyether B and, optionally, of a per(halo)fluoropolymer C advantageously enables improvement of rheological behavior of thermoplastic partially fluorinated fluoropolymer A, making possible processing in less severe conditions and yielding final parts with outstanding surface aspect and good homogeneity and coherency. Still objects of the inventions are the process for manufacturing said thermoplastic fluoropolymer composition and the articles thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage entry of International ApplicationNo. PCT/EP06/63589 , having an international filing date of Jun. 27,2006; which claims priority to European Application No.: 05106413.7,filed Jul. 13, 2005, the disclosures of each of which is herebyincorporated in its entirety by reference.

The invention pertains to thermoplastic halopolymer compositions, to aprocess for manufacturing said thermoplastic halopolymer compositionsand to the articles thereof.

Halopolymers, in particular fluorocarbon resins, are endowed withoutstanding mechanical properties within a broad range of temperature,excellent resistance to high temperature, organic solvents and tovarious chemically aggressive environments.

Thanks to their properties they are commonly used for manufacturingarticles by extrusion or injection molding, e.g. for producing pipes,tubes, fittings, films, coatings, cable sheathings, flexible pipes andthe like.

To further improve mechanical properties of these polymers, it is wellknown to increase their molecular weight, or, in other words, toincrease their melt viscosity. Thus, although halopolymers of high molarmass (and thus high melt viscosity) are preferable because of improvedmechanical properties, processing these materials is more difficult. Inparticular, in extrusion process, they display rheology problems,accounting for increased energy consumption during extrusion and moresevere extrusion conditions to be applied (with consequent risks ofthermal degradation of the polymer). In this case, finished parts(extrusion or injection molded) made from these halopolymers havegenerally surface defects like cracks, shark-skin, fish-eyes and thelike.

Processing aids have been thus largely used to obviate these problems;nevertheless, they have several drawbacks. Due to their limited thermalstability at processing temperature, benefits of their addition are lostand fumes are released during processing; thermal degradation residuesgenerate in final parts structural color (bad yellow indexes), defectsand voids that can be detrimental to mechanical properties. Moreover,due to their incompatibility with the halopolymer itself, they tend tosegregate and yield uneven dispersion, so that the benefits in improvingrheological behavior are lost.

This invention thus aims at providing a halopolymer composition withincreased processability and yielding finished parts with outstandingsurface aspect.

This problem is remarkably solved by the thermoplastic halopolymercomposition of the invention, comprising:

-   -   at least one thermoplastic halopolymer [polymer (A)];    -   from 0.01 to 5% by weight of (A) of at least one        (per)fluoropolyether [polymer (B)]; and    -   from 0.3 to 10% by weight of (A) of at least        per(halo)fluoropolymer [polymer (C)].

Another object of the invention is a process for manufacturing saidthermoplastic halopolymer compositions.

Still objects of the invention are the articles, such as shapedarticles, films, cable sheathing, pipes, flexible pipes, hollow bodiescomprising the thermoplastic halopolymer composition.

The addition of a (per)fluoropolyether (B) and of aper(halo)fluoropolymer (C) enables substantial improvement ofrheological behavior of thermoplastic halopolymer (A), making possibleprocessing in less severe conditions and yielding final parts withoutstanding surface aspect and good homogeneity and coherency.

Within the context of the present invention, the term “polymer”possesses its usual meaning, i.e. it denotes a material comprisingrecurring units and having a molecular weight exceeding 300.

Polymer (C) is preferably present in the composition in phase-separateddomains mainly comprising (C) in a continuous phase mainly comprisingpolymer (A), at least 75% by volume of said domains having maximaldimension not exceeding 20 μm.

Maximal dimension of said domains does not exceed preferably 10 μm, morepreferably 5 μm, even more preferably 1 μm.

The term “continuous phase mainly comprising (A)” is intended to denotea continuous phase comprising (A) as major component, i.e. comprisingmore than 50%, preferably more than 60%, still more preferably more than75% by weight of (A).

The term “phase-separated domains mainly comprising (C)” is intended todenote a phase comprising (C) as major component, i.e. comprising morethan 50%, preferably more than 60%, still more preferably more than 75%by weight of (C).

The term “phase-separated domain” is intended to denotethree-dimensional volume element of the composition of the invention,wherein the concentration of (C) is at least 25% higher, preferably 30%higher, still more preferably 50% higher than the concentration of (C)in the continuous phase mainly comprising (A).

The term “maximal dimension” is intended to denote the maximal value ofthe diameter of a cross-sectional area, associated to each of thepossible differently oriented cross-sections of the phase-separateddomain.

A cross section is to be intended as the intersection of thephase-separated domain in three-dimensional space with a plane. From apractical point of view, when cutting into slices, many parallel crosssections are obtained.

The diameter of a cross-sectional area is defined as the diameter of thesmallest circle which the cross-sectional area can be comprised in.

Maximal dimension of the phase-separated domains may be preferablydetermined by SEM microscopy and image recognition on samples of thecomposition, obtained from microtomic cuts or fractures, realized atliquid nitrogen temperature.

Volume percent of phase-separated domains having maximal dimension notexceeding a relevant value is calculated by measuring surface area ofsuch domains with respect to the total area of domains in the microtomiccut or fracture analyzed by SEM microscopy and image recognition.

The mention “at least one thermoplastic halopolymer (A)” is intended todenote one or more than one polymer (A).

The polymer (A) of the invention should be thermoplastic.

The term “thermoplastic” is understood to mean, for the purposes of thepresent invention, polymers existing, at room temperature, below theirglass transition temperature, if they are amorphous, or below theirmelting point if they are semi-crystalline, and which are linear (i.e.not reticulated). These polymers have the property of becoming soft whenthey are heated and of becoming rigid again when they are cooled,without there being an appreciable chemical change. Such a definitionmay be found, for example, in the encyclopedia called “Polymer ScienceDictionary”, Mark S. M. Alger, London School of Polymer Technology,Polytechnic of North London, UK, published by Elsevier Applied Science,1989.

Thermoplastic polymers are thus distinguishable from elastomers.

To the purpose of the invention, the term “elastomer” is intended todesignate a true elastomer or a polymer resin serving as a baseconstituent for obtaining a true elastomer.

True elastomers are defined by the ASTM, Special Technical Bulletin, No.184 standard as materials capable of being stretched, at roomtemperature, to twice their intrinsic length and which, once they havebeen released after holding them under tension for 5 minutes, return towithin 10% of their initial length in the same time.

Polymer resins serving as a base constituent for obtaining trueelastomers are in general amorphous products having a glass transitiontemperature (T_(g)) below room temperature. In most cases, theseproducts correspond to copolymers having a T_(g) below 0° C. andincluding reactive functional groups (optionally in the presence ofadditives) allowing the true elastomer to be formed.

Preferably, polymer (A) is semi-crystalline.

The term “semi-crystalline” is intended to denote a polymer having aheat of fusion of more than 1 J/g when measured by Differential ScanningCalorimetry (DSC) at a heating rate of 10° C./min, according to ASTM D3418.

Preferably, the polymer (A) of the invention has a heat of fusion of atleast 4 J/g, more preferably of at least 8 J/g.

To the purpose of the invention, the term “halopolymer” is intended todenote the homopolymers and copolymers obtained from monoethylenicmonomers containing at least 2 carbon atoms and at least one halogenatom chosen from fluorine and chlorine. It is also intended to denoteblends of homopolymers and copolymers. As examples of halopolymers thatmay be used in the present invention, mention may be made especially ofvinylidene fluoride, vinyl fluoride, trifluoroethylene,chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, vinylchloride and vinylidene chloride homopolymers and copolymers, and alsocopolymers of one of these monomers with another non-halogenatedmonoethylenic monomer such as ethylene, vinyl acetate and acrylic ormethacrylic monomers.

Preferably the halopolymer of the invention is a fluoropolymer, i.e. apolymer comprising recurring units derived from at least oneethylenically unsaturated monomer comprising at least one fluorine atom(hereinafter, fluorinated monomer).

More preferably, the halopolymer of the invention is a partiallyfluorinated fluoropolymer.

To the purpose of the present invention, the term “partially fluorinatedfluoropolymer” is intended to denote any polymer comprising:

-   -   recurring units derived from at least one fluorinated monomer;        and    -   recurring units derived from at least one ethylenically        unsaturated monomer comprising at least one hydrogen atom        (hereinafter, hydrogen-containing monomer).

The fluorinated monomer and the hydrogen-containing monomer may be thesame monomer or may be different monomers.

The partially fluorinated fluoropolymer comprises advantageously morethan 1% mol, preferably more than 5% mol, more preferably more than 10%mol of recurring units derived from the hydrogen-containing monomer.

The partially fluorinated fluoropolymer comprises advantageously morethan 25% mol, preferably more than 30% mol, more preferably more than40% mol of recurring units derived from the fluorinated monomer.

The fluorinated monomer can further comprise one or more other halogenatoms (Cl, Br, I). Should the fluorinated monomer be free of hydrogenatom, it is designated as per(halo)fluoromonomer. Should the fluorinatedmonomer comprise at least one hydrogen atoms, it is designated ashydrogen-containing fluorinated monomer.

Should the fluorinated monomer be a hydrogen-containing fluorinatedmonomer, such as for instance vinylidene fluoride, trifluoroethylene,vinylfluoride, the partially fluorinated fluoropolymer can be either ahomopolymer comprising recurring units derived from saidhydrogen-containing fluorinated monomer, or a copolymer comprisingrecurring units derived from said hydrogen-containing fluorinatedmonomer and from at least one other comonomer.

The comonomer can be either hydrogenated (i.e. free of fluorine atom) orfluorinated (i.e. containing at least one fluorine atom).

Should the fluorinated monomer be a per(halo)fluoromonomer, such as forinstance tetrafluoroethylene, chlorotrifluoroethylene,hexafluoropropylene, perfluoroalkylvinylethers, the partiallyfluorinated fluoropolymer is a copolymer comprising recurring unitsderived from said per(halo)fluoromonomer and from at least one othercomonomer, said comonomer comprising at least one hydrogen atom, such asfor instance ethylene, propylene, vinylethers, acrylic monomers,vinylidene fluoride, trifluoroethylene, vinylfluoride.

Preferred partially fluorinated fluoropolymer are those wherein thefluorinated monomer is chosen from the group consisting oftetrafluoroethylene (TFE), vinylidene fluoride (VdF) andchlorotrifluoroethylene (CTFE).

Non limitative examples of suitable hydrogenated comonomers are notablyethylene, propylene, vinyl monomers such as vinyl acetate, acrylicmonomers, like methyl methacrylate, butyl acrylate, acrylic acid,methacrylic acid and hydroxyethyl acrylate, as well as styrene monomers,like styrene and p-methylstyrene.

Non limitative examples of suitable fluorinated comonomers are notably:

-   -   C₃-C₈ perfluoroolefins, such as hexafluoropropene;    -   C₂-C₈ hydrogenated monofluoroolefins, such as vinyl fluoride;    -   1,2-difluoroethylene and trifluoroethylene;    -   perfluoroalkylethylenes complying with formula CH₂═CH—R_(f0), in        which R_(f0) is a C₁-C₆ perfluoroalkyl;    -   chloro- and/or bromo- and/or iodo-C₂-C₆ fluoroolefins, like        chlorotrifluoroethylene;    -   (per)fluoroalkylvinylethers complying with formula CF₂═CFOR_(f1)        in which R_(f1) is a C₁-C₆ fluoro- or perfluoroalkyl, e.g. CF₃,        C₂F₅, C₃F₇;    -   CF₂═CFOX₀ (per)fluoro-oxyalkylvinylethers, in which X₀ is a        C₁-C₁₂ alkyl, or a C₁-C₁₂ oxyalkyl, or a C₁-C₁₂        (per)fluorooxyalkyl having one or more ether groups, like        perfluoro-2-propoxy-propyl;    -   (per)fluoroalkylvinylethers complying with formula        CF₂═CFOCF₂OR_(f2) in which R_(f2) is a C₁-C₆ fluoro- or        perfluoroalkyl, e.g. CF₃, C₂F₅, C₃F₇ or a C₁-C₆        (per)fluorooxyalkyl having one or more ether groups, like        —C₂F₅—O—CF₃;    -   functional (per)fluoro-oxyalkylvinylethers complying with        formula CF₂═CFOY₀, in which Y₀ is a C₁-C₁₂ alkyl or        (per)fluoroalkyl, or a C₁-C₁₂ oxyalkyl, or a C₁-C₁₂        (per)fluorooxyalkyl having one or more ether groups and Y₀        comprising a carboxylic or sulfonic acid group, in its acid,        acid halide or salt form;    -   fluorodioxoles, especially perfluorodioxoles.

The melt index of the polymer (A) is preferably less than 10, preferablyless than 8, more preferably less than 7 g/10 min, even more preferablyless than 5 g/10 min, most preferably less than 2.5 g/10 min.

The melt flow index of the polymer (A) is advantageously measuredaccording to ASTM D-1238 standard under a piston load of 5 kg at atemperature chosen as a function of the chemical nature of polymer (A),as detailed in paragraph 8.2 of said standard.

When the MFI of polymer (A) is of 10 g/10 min or more, the thermoplasticcomposition does not possess the outstanding mechanical properties whichare sought for highly demanding applications.

More preferably, the partially fluorinated fluoropolymer are chosenamong:

-   (A-1) TFE and/or CTFE copolymers with ethylene, propylene or    isobutylene (preferably ethylene), with a molar ratio    per(halo)fluoromonomer(s)/hydrogenated comonomer(s) of from 30:70 to    70:30, optionally containing one or more comonomers in amounts of    from 0.1 to 30% by moles, based on the total amount of TFE and/or    CTFE and hydrogenated comonomer(s) (see for instance U.S. Pat. Nos.    3,624,250 and 4,513,129);-   (A-2) Vinylidene fluoride (VdF) polymers, optionally comprising    reduced amounts, generally comprised between 0.1 and 15% by moles,    of one or more fluorinated comonomer(s) (see for instance U.S. Pat.    Nos. 4,524,194 and 4,739,024), and optionally further comprising one    or more fluorinated or hydrogenated comonomer(s).

The CTFE or TFE copolymers (A-1) preferably comprise:

-   (a) from 35 to 65%, preferably from 45 to 55%, more preferably from    48 to 52% by moles of ethylene (E);-   (b) from 65 to 35%, preferably from 55 to 45%, more preferably from    52 to 48% by moles of chlorotrifluoroethylene (CTFE) (for the ECTFE    copolymers, hereinafter) and/or tetrafluoroethylene (TFE) (for the    ETFE copolymers, herein after); and optionally-   (c) from 0.1 to 30%, by moles, preferably 0.1 to 10% by moles, more    preferably 0.1 to 5% by moles, based on the total amount of    monomers (a) and (b), of one or more fluorinated comonomer(s) (c1)    and/or hydrogenated comonomer(s) (c2).

Among fluorinated comonomers (c1) we can for example mention(per)fluoroalkylvinylethers, perfluoroalkylethylenes (such asperfluorobutylethylene), (per)fluorodioxoles as described in U.S. Pat.No. 5,597,880), vinylidenefluoride (VdF). Among them, preferred (c1)comonomer is perfluoropropylvinylether of formula CF₂═CFO—C₃F₇.

As non limitative examples of hydrogenated comonomers (c2), mention maybe notably made of those having the general formula:CH₂═CH—(CH₂)_(n)R₁  (I)wherein R₁═OR₂, or —(O)_(t)CO(O)_(p)R₂ wherein t and p are integersequal to 0, 1 and R₂ is a C₁-C₂₀ hydrogenated radical, of alkyl type,linear or branched when possible, or cycloalkyl, optionally containingheteroatoms and/or chlorine atoms, the heteroatoms preferably being O orN, R₂ optionally contains one or more functional groups, preferablyselected from —OH, —COOH, epoxide, ester and ether, R₂ optionallycontains double bonds, or R₂ is H, n is an integer in the range 0-10.Preferably R₂ is hydrogen or of alkyl type from 1 to 10 carbon atomscontaining functional groups of hydroxide type, n is an integer in therange 0-5.

The preferred hydrogenated comonomers (c2) are selected from thefollowing classes:

-   1) Acrylic monomers having the general formula:    CH₂═CH—CO—O—R₂    -   wherein R₂ has the above mentioned meaning.    -   As non limitative examples of suitable acrylic monomers, mention        can be notably made of ethylacrylate, n-butylacrylate, acrylic        acid, hydroxyethylacrylate, hydroxypropylacrylate,        (hydroxy)ethylhexylacrylate.-   2) Vinylether monomers having the general formula:    CH₂═CH—O—R₂    -   wherein R₂ has the above mentioned meaning.    -   As non limitative examples of suitable vinylether monomers,        mention can be notably made of propylvinylether,        cyclohexylvinylether, vinyl-4-hydroxybutylether.-   3) Vinyl monomers of the carboxylic acid having the general formula:    CH₂═CH—O—CO—R₂    -   wherein R₂ has the above mentioned meaning.    -   As non limitative examples of suitable vinyl monomers of the        carboxylic acid, mention can be notably made of vinyl-acetate,        vinylpropionate, vinyl-2-ethylhexanoate.-   4) Unsaturated carboxylic acid monomers having the general formula:    CH₂═CH—(CH₂)_(n)—COOH    -   wherein n has the above mentioned meaning. As non limitative        example of suitable unsaturated carboxylic acid monomer, mention        can be notably made of vinylacetic acid.

More preferred comonomer (c2) is n-butylacrylate.

Among A-1 polymers, ECTFE polymers are preferred.

The melt index of the ECTFE is advantageously at least 0.01, preferablyat least 0.05, more preferably at least 0.1 g/10 min.

The melt index of the ECTFE is advantageously less than 10, preferablyless than 7.5, more preferably less than 5 g/10 min, even morepreferably less than 2.5 g/10 min.

The melt index of ECTFE is measured in accordance with modified ASTMtest No. 1238, run at 275° C., under a piston load of 5 kg.

The ECTFE has a melting point advantageously of at least 150° C. and atmost 265° C.

The melting point is determined by Differential Scanning Calorimetry(DSC) at a heating rate of 10° C./min, according to ASTM D 3418Standard.

Particularly adapted to thermoplastic halogenated polymer composition ofthe invention is ECTFE available from Solvay Solexis Inc., Thorofare,N.J., USA, under the tradename HALAR® and VATAR®.

Most preferably, the partially fluorinated fluoropolymer is a VdFpolymer (A-2).

The VdF polymers (A-2) preferably comprise:

-   (a′) at least 60% by moles, preferably at least 75% by moles, more    preferably at least 85% by moles of vinylidene fluoride (VdF);-   (b′) optionally from 0.1 to 15%, preferably from 0.1 to 12%, more    preferably from 0.1 to 10% by moles of a fluorinated comonomer    chosen among vinylfluoride (VF₁), chlorotrifluoroethylene (CTFE),    hexafluoropropene (HFP), tetrafluoroethylene (TFE),    trifluoroethylene (TrFE), perfluoromethylvinylether (PMVE) and    mixtures therefrom; and-   (c′) optionally from 0.1 to 5%, by moles, preferably 0.1 to 3% by    moles, more preferably 0.1 to 1% by moles, based on the total amount    of monomers (a′) and (b′), of one or more fluorinated or    hydrogenated comonomer(s).

As non limitative examples of the VdF polymers useful in the presentinvention, mention can be notably made of homopolymer of VdF, VdF/TFEcopolymer, VdF/PMVE copolymer, VdF/TFE/HFP copolymer, VdF/TFE/CTFEcopolymer, VdF/TFE/TrFE copolymer, VdF/CTFE copolymer, VdF/HFPcopolymer, VdF/TFE/HFP/CTFE copolymer, VdF/TFE/perfluorobutenoic acidcopolymer, VdF/TFE/maleic acid copolymer and the like.

The melt index of the VdF polymer is advantageously at least 0.01,preferably at least 0.05, more preferably at least 0.1 g/10 min.

The melt index of the VdF polymer is advantageously less than 10,preferably less than 7.5, more preferably less than 5 g/10 min, evenmore preferably less than 1 g/10 min.

The melt index of VdF polymer is measured in accordance with ASTM testNo. 1238, run at 230° C., under a piston load of 5 kg.

The VdF polymer has a melting point advantageously of at least 120° C.,preferably at least 125° C., more preferably at least 130° C.

The VdF polymer has a melting point advantageously of at most 190° C.,preferably at most 185° C., more preferably at most 180° C.

The melting point (T_(m2)) is determined by DSC, at a heating rate of10° C./min, according to ASTM D 3418.

According to a preferred embodiment of the invention, the polymer (A) isadvantageously a mixture of at least one VdF homopolymer and at leastone VdF copolymer chosen among the group consisting of VdF copolymercomprising from 0.1 to 15%, preferably from 0.1 to 12%, more preferablyfrom 0.1 to 10% by moles of a fluorinated comonomer chosen amongvinylfluoride (VF₁), chlorotrifluoroethylene (CTFE), hexafluoropropene(HFP), tetrafluoroethylene (TFE), trifluoroethylene (TrFE) and mixturesthereof.

Preferably, polymer (A) is a mixture of at least one VdF homopolymer andat least one VdF copolymer as above described, wherein the fluorinatedcomonomer is chosen among chlorotrifluoroethylene and hexafluoropropene.

The polymer (A) according to this preferred embodiment is morepreferably a mixture comprising:

-   -   advantageously from 25 to 75%, preferably from 25 to 65%, more        preferably from 25 to 55% by weight of polymer (A) of at least        one VdF homopolymer;    -   advantageously from 25 to 75%, preferably from 35 to 75%, more        preferably from 45 to 75% by weight of polymer (A) of at least        one VdF copolymer as above described.

Within the context of the present invention, the term(per)fluoropolyether is intended to denote a polymer comprisingrecurring units (R1), said recurring units comprising at least one etherlinkage in the main chain and at least one fluorine atom(fluoropolyoxyalkene chain).

Preferably the recurring units R1 of the (per)fluoropolyether areselected from the group consisting of:

-   (I) —CFX—O—, wherein X is —F or —CF₃; and-   (II) —CF₂—CFX—O—, wherein X is —F or —CF₃; and-   (III) —CF₂—CF₂—CF₂—O—; and-   (IV) —CF₂—CF₂—CF₂—CF₂—O—; and-   (V) —(CF₂)_(j)—CFZ-O— wherein j is an integer chosen from 0 and 1    and Z is a fluoropolyoxyalkene chain comprising from 1 to 10    recurring units chosen among the classes (I) to (IV) here above;    and mixtures thereof.

Should the (per)fluoropolyether comprise recurring units R1 of differenttypes, advantageously said recurring units are randomly distributedalong the fluoropolyoxyalkene chain.

Preferably the (per)fluoropolyether is a compound complying with formula(I) here below:T₁-(CFX)_(p)—O—R_(f)—(CFX)_(p′)-T₂  (I)wherein:

-   -   each of X is independently F or CF₃;    -   p and p′, equal or different each other, are integers from 0 to        3;    -   R_(f) is a fluoropolyoxyalkene chain comprising repeating units        R^(o), said repeating units being chosen among the group        consisting of:        -   (i) —CFXO—, wherein X is F or CF₃,        -   (ii) —CF₂CFXO—, wherein X is F or CF₃,        -   (iii) —CF₂CF₂CF₂O—,        -   (iv) —CF₂CF₂CF₂CF₂O—,        -   (v) —(CF₂)_(j)—CFZ-O— wherein j is an integer chosen from 0            and 1 and Z is a group of general formula —OR_(f)′T₃,            wherein R_(f)′ is a fluoropolyoxyalkene chain comprising a            number of repeating units from 0 to 10, said recurring units            being chosen among the followings: —CFXO—, —CF₂CFXO—,            —CF₂CF₂CF₂O—, —CF₂CF₂CF₂CF₂O—, with each of each of X being            independently F or CF₃; and T₃ is a C₁-C₃ perfluoroalkyl            group,        -   and mixtures thereof;    -   T₁ and T₂, the same or different each other, are H, halogen        atoms, C₁-C₃₀ end-group optionally comprising heteroatoms chosen        among O, S, N, and/or halogen atoms.

The weight average molecular mass of the (per)fluoropolyether isgenerally comprised between 400 and 100 000, preferably between 600 and20 000.

Preferably, the T₁ and T₂ are selected from the group consisting of:

-   (j) —Y′, wherein Y′ is chain end chosen among —H, halogen, such as    —F, —Cl, C₁-C₃ perhalogenated alkyl group, such as —CF₃, —C₂F₅,    —CF₂Cl, —CF₂CF₂Cl;-   (jj) —E_(r)-A_(q)-Y″_(k), wherein k, r and q are integers, with q=0    or 1, r=0 or 1, and k between 1 and 4, preferably between 1 and 2, E    denotes a functional linking group comprising at least one    heteroatom chosen among O, S, N; A denotes a C₁-C₂₀ bivalent linking    group; and Y″ denotes a functional end-group.

The functional group E may comprise an amide, ester, carboxylic,thiocarboxylic, ether, heteroaromatic, sulfide, amine, and/or iminegroup.

Non limitative examples of functional linking groups E are notably—CONR— (R═H, C₁-C₁₅ substituted or unsubstituted linear or cyclicaliphatic group, C₁-C₁₅ substituted or unsubstituted aromatic group);—COO—; —COS—; —CO—; an heteroatom such as —O—; —S—; —NR′—(R═H, C₁-C₁₅substituted or unsubstituted linear or cyclic aliphatic group, C₁-C₁₅substituted or unsubstituted aromatic group); a 5- or 6-memberedaromatic heterocycle containing one or more heteroatoms chosen among N,O, S, the same or different each other, in particular triazines, such as

The bivalent C₁-C₂₀ linking group A is preferably selected from thefollowing classes:

-   1) linear substituted or unsubstituted C₁-C₂₀ alkylenic chain,    optionally containing heteroatoms in the alkylenic chain; preferably    linear aliphatic group comprising moieties of formula —(CH₂)_(m)—,    with m integer between 1 and 20, and optionally comprising amide,    ester, ether, sulfide, imine groups and mixtures thereof;-   2) (alkylene)cycloaliphatic C₁-C₂₀ groups or (alkylen)aromatic    C₁-C₂₀ groups, optionally containing heteroatoms in the alkylenic    chain or in the ring, and optionally comprising amide, ester, ether,    sulfide, imine groups and mixtures thereof;-   3) linear or branched polyalkylenoxy chains, comprising in    particular repeating units selected from: —CH₂CH₂O—, —CH₂CH(CH₃)O—,    —(CH₂)₃O—, —(CH₂)₄O—, optionally comprising amide, ester, ether,    sulfide, imine groups and mixtures thereof.

Examples of suitable functional groups Y″ are notably —OH, —SH, —OR′,—SR′, —NH₂, —NHR′, —NR′₂, —COOH, —SiR′_(d)Q_(3-d), —CN, —NCO,

1,2- and 1,3-diols as such or as cyclic acetals and ketals (e.g.,dioxolanes or dioxanes), —COR′, —CH(OCH₃)₂, —CH(OH)CH₂OH, —CH(COOR′)₂,—CH(COOH)₂, —CH(CH₂OH)₂, —CH(CH₂NH₂)₂, —PO(OH)₂, —CH(CN)₂, wherein R′ isan alkyl, cycloaliphatic or aromatic substituted or unsubstituted group,optionally comprising one or more fluorine atoms, Q is OR′, R′ havingthe same meaning as above defined, d is an integer between 0 and 3.

One or more functional end-groups Y″ can be linked to the group A and/orE: for instance, when A is an (alkylen)aromatic C₁-C₂₀ group, it ispossible that two or more Y″ groups are linked to the aromatic ring ofthe group A.

More preferably, the (per)fluoropolyether of the invention complies withformula (I) here above, wherein the T₁ and T₂ are selected from thegroup consisting of: —H; halogen such as —F and —Cl; C₁-C₃perhalogenated alkyl group, such as —CF₃, —C₂F₅, —CF₂Cl, —CF₂CF₂Cl;—CH₂OH; —CH₂(OCH₂CH₂)_(n)OH (n being an integer between 1 and 3);—C(O)OH; —C(O)OCH₃; —ONH—R_(H)—OSi(OC₂H₅)₃ (where R_(H) is a C₁-C₁₀alkyl group); —CONHC₁₈H₃₇; —CH₂OCH₂CH(OH)CH₂OH;—CH₂O—(CH₂CH₂O)_(n).PO(OH)₂ (with n* between 1 and 3);

and mixtures thereof.

Most preferably, the (per)fluoropolyethers suitable for the inventionare chosen among the group consisting of:

-   (a) HO—CH₂CF₂O(CF₂O)_(n′)(CF₂CF₂O)_(m′)CF₂CH₂—OH, m′ and n′ being    integers, where the ratio m′/n′ generally ranges between 0.1 and 10,    preferably between 0.2 and 5;-   (b)    HO(CH₂CH₂O)_(n)CH₂CF₂O(CF₂O)_(n′)(CF₂CF₂O)_(m′)CF₂CH₂(OCH₂CH₂)_(n)OH,    m′ and n′ being integers, where the ratio m′/n′ generally ranges    between 0.1 and 10, preferably between 0.2 and 5, and n ranges    between 1 and 3;-   (c) HCF₂O(CF₂O)_(n′)(CF₂CF₂O)_(m′)CF₂H, m′ and n′ being integers,    where the ratio m′/n′ generally ranges between 0.1 and 10,    preferably between 0.2 and 5;-   (d) FCF₂O(CF₂O)_(n′)(CF₂CF₂O)_(m′)CF₂F, m′ and n′ being integers,    where the ratio m′/n′ generally ranges between 0.1 and 10,    preferably between 0.2 and 5.

Excellent results have been obtained with thermoplastic halopolymercompositions comprising a (per)fluoropolyether chosen among types (a)and (b) here above.

The (per)fluoropolyethers of the invention can be notably manufacturedby photoinitiated oxidative polymerization (photooxidation reaction) ofper(halo)fluoromonomers, as described in U.S. Pat. No. 3,665,041.Typically, (per)fluoropolyethers structures can be obtained bycombination of hexafluoropropylene and/or tetrafluoroethylene withoxygen at low temperatures, in general below −40° C., under U.V.irradiation, at a wavelength (λ) of less than 3 000 Å. Subsequentconversion of end-groups as described in U.S. Pat. Nos. 3,847,978 and3,810,874 is notably carried out on crude products from photooxidationreaction.

The (per)fluoropolyethers of types (a), (b), (c), and (d) as abovedescribed, are notably available from Solvay Solexis S.p.A. as FOMBLIN®ZDOL, FOMBLIN® ZDOL TX, H-GALDEN® and FOMBLIN® Z or FOMBLIN® M.

The amount of (per)fluoropolyether (B) in the multi-phase thermoplastichalopolymer composition as above described is of preferably at least0.02%, more preferably at least 0.05% by weight of the thermoplastichalopolymer (A).

The amount of (per)fluoropolyether (B) in the multi-phase thermoplastichalopolymer composition as above described is of preferably at most 4%,more preferably at most 3% by weight of the thermoplastic halopolymer(A).

Good results have been obtained with composition comprising from 0.05 to5% by weight of (A) of (per)fluoropolyether (B).

Excellent results have been obtained with composition comprising from0.05 to 0.5% by weight of (A) of (per)fluoropolyether (B).

Thank to the presence of the (per)fluoropolyether (B), the compositioncomprising the thermoplastic halopolymer (A) can be advantageouslyprocessed at higher throughput rate and final parts so obtained possessexcellent surface aspect, with no visual defects.

For the purpose of the invention, the term “per(halo)fluoropolymer”[polymer (C)] is intended to denote a fluoropolymer substantially freeof hydrogen atoms.

The per(halo)fluoropolymer can further comprise one or more otherhalogen atoms (Cl, Br, I).

The term “substantially free of hydrogen atom” is understood to meanthat the per(halo)fluoropolymer is prepared from ethylenicallyunsaturated monomers comprising at least one fluorine atom and free ofhydrogen atoms (per(halo)fluoromonomer).

The per(halo)fluoropolymer can be a homopolymer of aper(halo)fluoromonomer or a copolymer comprising recurring units derivedfrom more than one per(halo)fluoromonomers.

Non limitative examples of suitable per(halo)fluoromonomers are notably:

-   -   C₂-C₈ perfluoroolefins, such as tetrafluoroethylene and        hexafluoropropene;    -   chloro- and/or bromo- and/or iodo-C₂-C₆ fluoroolefins, like        chlorotrifluoroethylene;    -   per(halo)fluoroalkylvinylethers complying with general formula        CF₂═CFOR_(f3) in which R_(f3) is a C₁-C₆ per(halo)fluoroalkyl,        such as —CF₃, —C₂F₅, —C₃F₇;    -   CF₂═CFOX₀₁ per(halo)fluoro-oxyalkylvinylethers, in which X₀₁ is        a C₁-C₁₂ per(halo)fluorooxyalkyl having one or more ether        groups, like perfluoro-2-propoxy-propyl group;    -   Per(halo)fluoroalkylvinylethers complying with general formula        CF₂═CFOCF₂ORf₄ in which R_(f4) is a C₁-C₆ or        per(halo)fluoroalkyl, such as —CF₃, —C₂F₅, —C₃F₇ or a C₁-C₆        per(halo)fluorooxyalkyl having one or more ether groups,        —C₂F₅—O—CF₃;    -   functional per(halo)fluoro-oxyalkylvinylethers complying with        formula CF₂═CFOY₀₁, in which Y₀₁ is a C₁-C₁₂        per(halo)fluoroalkyl, or a C₁-C₁₂ per(halo)fluorooxyalkyl having        one or more ether groups, and Y₀₁ comprising a carboxylic or        sulfonic acid group, in its acid, acid halide or salt form;    -   per(halo)fluorodioxoles.

Suitable examples of per(halo)fluoropolymer [polymer (C)] useful in thecomposition according to the invention are notably TFE homopolymers andcopolymers and CTFE homopolymers and copolymers.

Preferred per(halo)fluoropolymer [polymer (C)] are notably TFEhomopolymers and copolymers.

Should the polymer (C) be a TFE homopolymer, it is preferably a nonfibrillating PTFE (commonly also referred to as “low molecular weightPTFE” or “low melt viscosity PTFE”).

The non fibrillating PTFE has an average molecular weight in number ofadvantageously below 1 000 000, preferably below 700 000, morepreferably below 500 000.

Besides, the non fibrillating PTFE has preferably an average molecularweight in number of preferably above 50 000.

The number average molecular weight of the non fibrillating is generallycalculated by measuring the total amount N_(g) (expressed in moles/kg)of the PTFE end groups —CF₂COOH and —CF₂COF, determined by FT-IRspectroscopy. The number average molecular weight (M_(n)) is calculatedby means of the following formula M_(n)=2 000/N_(g).

The non fibrillating PTFE has preferably a melt viscosity of below 10⁴Pa×s, as measured at 372° C. in accordance with the procedure ASTMD1239-52T, modified as described in U.S. Pat. No. 4,380,618.

The non fibrillating PTFE is preferably obtained by irradiating withgamma rays or electron beam powders of high molecular weight homopolymerof TFE (typically, with an average molecular weight in number above 2000 000) obtained by dispersion or suspension polymerization processesand then milling said irradiated powders, or directly by polymerizationtechnique such as described in example 1 of U.S. Pat. No. 5,223,343.

The non fibrillating PTFE is usually in the form of finely dividedsolids, and is then commonly referred to as “PTFE micropowder”. Thefinely divided solids have an average particle size of preferably lessthan 100 μm, more preferably less than 20 μm, still more preferably lessthan 10 μm and the most preferably less than 5 μm.

With the dispersion polymerization processes latexes having a particlesize of 0.1-0.3 micron are generally obtained. After coagulation thepowder particle sizes increase usually to about 100-500 micron. Saidpowders are then in general irradiated with gamma rays and then milledto obtain finely divided solids as above specified.

With the suspension polymerization processes, powders having particlesizes of 2-5 mm are generally obtained. Said powders are in generalirradiated with electron beam and then milled to obtain finely dividedsolids as above specified.

The non fibrillating PTFE has preferably thermal stability, chemicalinertness, lubricity, and high melting temperature similar to highmolecular weight PTFEs.

Especially suitable non fibrillating PTFE are ALGOFLON® L 206 and L 203PTFE and POLYMIST® PTFE, available from Solvay Solexis, S.p.A. Othersuitable non fibrillating PTFEs are commercially available notably fromDuPont as ZONYL® PTFE (e.g. ZONYL® MP1600 grade), and from DaikinIndustries, Ltd. as LUBLON® (e.g. LUBLON® L-5 PTFE).

Should the polymer (C) be a TFE copolymer, it comprises advantageouslyat least 2% wt, preferably at least 7% wt, and advantageously at most30% wt, preferably at most 20% wt, more preferably at most 13% wt ofrecurring units derived from at least one fluorinated comonomer chosenamong the group consisting of:

-   (i) perfluoroalkylvinylethers complying with formula CF₂═CFOR_(f1′),    in which R_(f1′) is a C₁-C₆ perfluoroalkyl, e.g. CF₃, C₂F₅, C₃F₇;    and/or-   (ii) perfluoro-oxyalkylvinylethers complying with formula CF₂═CFOX₀,    in which X₀ is a C₁-C₁₂ perfluorooxyalkyl having one or more ether    groups, like perfluoro-2-propoxy-propyl; and/or-   (iii) C₃-C₈ perfluoroolefins, such as hexafluoropropylene.

Good results have been obtained with TFE copolymers wherein thefluorinated comonomer is a C₃-C₈ perfluoroolefin and/or aperfluoroalkylvinylether as above specified; particularly good resultshave been achieved with TFE copolymers wherein the fluorinated comonomeris hexafluoropropylene and/or perfluoromethylvinylether (PMVE) (offormula CF₂═CFOCF₃).

Shall the polymer (C) be a TFE copolymer wherein the fluorinatedcomonomer is a perfluoroalkylvinylether as above specified, said TFEcopolymer has a dynamic viscosity at a shear rate of 1 s⁻¹ ofadvantageously at most 100 Pa×sec, preferably of at most 50 Pa×sec, morepreferably of at most 30 Pa×sec, most preferably of at most 10 Pa×sec ata temperature of 280° C.

Dynamic viscosity is typically measured with a controlled strainrheometer, employing an actuator to apply a deforming strain to thesample and a separate transducer to measure the resultant stressdeveloped within the sample, using the parallel plate fixture.

According to an embodiment of the invention, the polymer (C) ispreferably a tetrafluoroethylene (TFE)/perfluoromethylvinylether (PMVE)copolymer consisting essentially of:

-   -   from 4 to 25% moles, preferably from 5 to 20% wt, most        preferably from 10 to 16% moles of recurring units derived from        PMVE; and    -   from 96 to 75% moles, preferably from 95 to 80, most preferably        from 90 to 84% moles of recurring units derived from TFE.

Preferably the polymer (C) is melt-processible.

For the purposes of the present invention, by the term“melt-processible” is meant that the per(halo)fluoropolymer (C) can beprocessed (i.e. fabricated into shaped articles such as films, fibers,tubes, wire coatings and the like) by conventional melt extruding,injecting or casting means. Such typically requires that the dynamicviscosity at a shear rate of 1 s⁻¹ and at a temperature exceedingmelting point of roughly 30° C., preferably at a temperature ofT_(m2)+(30±2° C.), is of less than 10⁶ Pa×s, when measured with acontrolled strain rheometer, employing an actuator to apply a deformingstrain to the sample and a separate transducer to measure the resultantstress developed within the sample, and using the parallel platefixture.

The melting point (T_(m2)) is determined by DSC, at a heating rate of10° C./min, according to ASTM D 3418.

The melt processible per(halo)fluoropolymer (C) has a dynamic viscosityat a shear rate of 1 s⁻¹ in the above specified conditions preferably ofless than 2 000 Pa×s, more preferably of less than 700 Pa×s.

Should the polymer (C) be melt-processible, the ratio between the meltindex of the polymer (C) and the melt index of the polymer (A) isadvantageously at least 5, preferably at least 10, more preferably atleast 20.

The melt index of polymer (C) is measured in accordance with ASTM testNo. 1238.

The amount of per(halo)fluoropolymer (C) in the thermoplastichalopolymer composition as above described is of advantageously at least0.3%, preferably at least 1% by weight of the thermoplastic halopolymer(A). The amount of per(halo)fluoropolymer (C) in the thermoplastichalopolymer composition as above described is of advantageously at most10%, preferably at most 5%, more preferably at most 4% by weight of thethermoplastic halopolymer (A).

Good results have been obtained with thermoplastic halopolymercomposition comprising from 0.3 to 10% of per(halo)fluoropolymer (C) byweight of thermoplastic halopolymer (A). Best results have been achievedwith thermoplastic fluoropolymer composition comprising from 1 to 3% ofper(halo)fluoropolymer (C) by weight of thermoplastic halopolymer (A).

When a per(halo)fluoropolymer (C) is present in the compositioncomprising the thermoplastic halopolymer (A) and the(per)fluoropolyether (B), the processability of the composition isadvantageously further improved. Thus, at comparable throughput in theextruder, composition further comprising the per(halo)fluoropolymer (C)can be extruded at lower head pressure than the composition free ofpolymer (C).

Optionally, the composition described above can further comprisepigments, filling materials, electrically conductive particles, moldrelease agents, heat stabilizer, anti-static agents, extenders,reinforcing agents, organic and/or inorganic pigments like TiO₂, carbonblack, acid scavengers, such as MgO, flame-retardants, smoke-suppressingagents and the like.

By way of non-limiting examples of filling material, mention may be madeof mica, alumina, talc, carbon black, glass fibers, carbon fibers,graphite in the form of fibers or of powder, carbonates such as calciumcarbonate, macromolecular compounds and the like.

Pigments useful in the composition notably include, or will comprise,one or more of the following: titanium dioxide which is available formWhittaker, Clark & Daniels, South Plainfield, N.J., USA; Artic blue #3,Topaz blue #9, Olympic blue #190, Kingfisher blue #211, Ensign blue#214, Russet brown #24, Walnut brown #10, Golden brown #19, Chocolatebrown #20, Ironstone brown #39, Honey yellow #29, Sherwood green #5, andJet black #1 available from Shepard Color Company, Cincinnati, Ohio,USA.; black F-2302, blue V-5200, turquoise F-5686, green F-5687, brownF-6109, buff F-6115, chestnut brown V-9186, and yellow V-9404 availablefrom Ferro Corp., Cleveland, Ohio, USA and METEOR® pigments availablefrom Englehard Industries, Edison, N.J., USA.

According to an embodiment of the invention, the composition furthercomprises a plasticizer.

Plasticizers suitable for the composition of the invention may be chosenfrom the usual monomeric or polymeric plasticizers for fluoropolymers.

Plasticizers described in U.S. Pat. No. 3,541,039 (PENNWALT CORP) 17Nov. 1970 and those described in U.S. Pat. No. 4,584,215 (INST FRANCAISDU PETROL (FR)) 22 Apr. 1986 are suitable for the compositions of theinvention.

The plasticizers are incorporated without any difficulty in thecompositions of the invention defined above and produce compositionswhose impact strength, especially at low temperature, is advantageouslyimproved. In other words, plasticizers can be advantageously used in thecompositions of the invention to improve the low temperature behaviourof final parts made from inventive compositions, especially when theseparts are submitted to extreme operating temperatures.

Among monomeric plasticizers, mention can be notably made of dibutylsebacate (DBS), N-n-butylsulphonamide, acetyl-tri-n-butylcitrate offormula:

and dibutoxyethyladipate of formula:

A plasticizer which has shown itself to be particularly advantageouswithin the context of the present invention is DBS(C₄H₉—OOC—(CH₂)₈—COO—C₄H₉).

Among polymeric plasticizers, mention can be notably made of polymericpolyesters such as those derived from adipic, azelaic or sebacic acidsand diols, and their mixtures, but on condition that their molecularmass is at least approximately 1500, preferably at least 1800, and notexceeding approximately 5000, preferably lower than 2500. Polyesters ofexcessively high molecular mass result, in fact, in compositions oflower impact strength.

Should the composition of the invention comprise a plasticizer, theamount of plasticizer is of advantageously at least 1%, preferably of atleast 2% and advantageously of at most 20%, preferably of at most 10% byweight of polymer (A).

Another aspect of the present invention concerns a process formanufacturing the thermoplastic halopolymer composition as abovedescribed, said process comprising mixing:

-   (i) the thermoplastic halopolymer (A);-   (ii) the (per)fluoropolyether (B);-   (iii) the per(halo)fluoropolymer (C); and-   (iv) optionally, other additives or filling materials.

The process of the invention encompasses the simultaneous mixing ofpolymer (A), polymer (B) and polymer (C) or the mixing of two of saidcomponents in a first step, followed by mixing the so obtained admixturewith the remaining component in a further step.

According to a preferred variant of the invention, the process comprisesmixing by dry blending and/or melt compounding polymer (A), polymer (B)and polymer (C).

Preferably, the process comprises melt compounding polymer (A), polymer(B) and polymer (C).

Advantageously, the polymer (A), the polymer (B) and the polymer (C) aremelt compounded in continuous or batch devices. Such devices arewell-known to those skilled in the art.

Examples of suitable continuous devices to melt compound thethermoplastic halopolymer composition of the invention are notably screwextruders. Thus, the polymer (A), the polymer (B), the polymer (C) andoptionally other ingredients, are advantageously fed in an extruder andthe thermoplastic halopolymer composition is extruded.

This operating method can be applied either with a view to manufacturingfinished product such as, for instance, hollow bodies, pipes, laminates,calendared articles, or with a view to having available granulescontaining the desired composition, optionally additives and fillers, insuitable proportions in the form of pellets, which facilitates asubsequent conversion into finished articles. With this latter aim, thethermoplastic halopolymer composition of the invention is advantageouslyextruded into strands and the strands are chopped into pellets.

Optionally, fillers, heat stabilizer, anti-static agents, extenders,reinforcing agents, organic and/or inorganic pigments like TiO₂, carbonblack, acid scavengers, such as MgO, flame-retardants, smoke-suppressingagents, plasticizer(s) may be added to the composition during thecompounding step.

Preferably, the polymer (A), the polymer (B) and the polymer (C) aremelt compounded in a twin-screw extruder. Examples of suitable extruderswell-adapted to the process of the invention are those available fromWerner and Pfleiderer and from Farrel.

The process advantageously comprises mixing said polymer (C) under theform of particles having an average primary particle size of less than300 nm, preferably less than 200 nm, even more preferably of less than150 nm.

For the purpose of the invention the term “particle” is intended todenote a mass of material that, from a geometrical point of view, has adefinite three-dimensional volume and shape, characterized by threedimensions, wherein none of said dimensions exceed the remaining twoother dimensions of more than 200%. Particles are generally notequidimensional, i.e. that are longer in one direction than in others.

The shape of a particle can be notably expressed in terms of thesphericity Φ_(s), which is independent of particle size. The sphericityof a particle is the ratio of the surface-volume ratio of a sphere withequal volume as the particle and the surface-volume ratio of theparticle. For a spherical particle of diameter D_(p), Φ_(s)=1; for anon-spherical particle, the sphericity is defined as

wherein:

-   -   D_(p) is the equivalent diameter of particle;    -   S_(p) is the surface area of one particle;    -   v_(p) is the volume of one particle.    -   The equivalent diameter is defined as the diameter of a sphere        of equal volume. D_(p) is usually taken to be the nominal size        based on screen analysis or microscopic analysis. The surface        area is found from adsorption measurements or from the pressure        drop in a bed of particles.

The primary particles of polymer (C) of the invention have a sphericityΦ_(s) of advantageously at least 0.6, preferably at least 0.65, morepreferably at least 0.7. Good results have been obtained with primaryparticles having a Φ_(s) from 0.7 to 0.95.

Primary particles of polymer (C) are generally obtained from emulsionpolymerization and can be converted to agglomerates (i.e. collection ofprimary particles) in the recovery and conditioning steps of polymer (C)manufacture, like notably concentration and/or coagulation of polymer(C) latexes and subsequent drying and homogenization.

The term particles is thus to be intended distinguishable from pellets,which are obtained when extruding polymer (C) in the molten state intostrands and chopping the strands into pellets.

Within the context of this invention, the term primary particle size isintended to denote the smallest size of particles of polymer (C)achieved during polymer (C) manufacture.

Should the polymer (C) not be submitted to conditions whereinagglomeration of primary particles occurs, then the average particlessize of polymer (C) is equal to the average primary particles size.

On the contrary, should the polymer (C) submitted to conditions whereinagglomeration of primary particles takes place, then the averageparticle size of the polymer (C) is different (notably larger) from theaverage primary particle size.

The average primary particle size of the per(halo)fluoropolymer (C) canbe advantageously measured by the dynamic laser light scattering (DLLS)technique according to the method described in B. Chu “Laser lightscattering” Academic Press, New York (1974).

According to a first embodiment of the preferred variant of theinvention, the process comprises mixing the polymer (A) and the polymer(C) under the form of latexes. Polymer (B) can be added in a furthermixing step, or can be simultaneously admixed with (A) and (C).

The process according to the first embodiment of the preferred variantof the invention preferably comprises the following steps:

-   -   mixing a latex of polymer (A) with a latex of polymer (C), to        obtain a latexes mixture;    -   coagulating said latexes mixture;    -   mixing said coagulated latexes mixture with the polymer (B) by        dry blending and/or melt compounding.

Said latexes mixture can be advantageously coagulated by adding acoagulant. Suitable coagulants are those known in the coagulation offluoropolymers latexes, for example aluminium sulfate, nitric acid,chlorhydric acid, calcium chloride. Calcium chloride is preferred. Theamount of coagulants depends on the type of the used coagulant. Amountsin the range from 0.001% to 30% by weight with respect to the totalamount of water in the latexes mixture, preferably in the range from0.01% to 5% by weight, can be used.

The process according to the first embodiment of the preferred variantof the invention can further comprise a separation step for the recoveryof the coagulated latexes mixture, and/or a drying step.

According to a second embodiment of the preferred variant of theinvention, the process comprises mixing by synthesizing polymer (A) inthe presence of polymer (C). Polymer (B) can be added in a furthermixing step, or can be simultaneously admixed with (A) and (C).

The process according to the second embodiment of the preferred variantof the invention advantageously comprises the following steps:

-   -   introducing in the reaction medium the particles of polymer (C);    -   preparing in said reaction medium the polymer (A) to obtain a        mixture of polymers (A) and (C);    -   mixing said mixture of polymers (A) and (C) with polymer (B) by        dry blending and/or melt compounding.

The particles of polymer (C) may be introduced in the reaction mediumunder the form of dry particles, latex or dispersion.

Preferably the particles of polymer (C) are added under the form oflatex.

Should the particles of polymer (C) be introduced under the form oflatex, said latex can be advantageously coagulated by adding a coagulantin the reaction medium. The coagulants for the polymer (C) are thoseknown in the coagulation of fluoropolymers latexes, for examplealuminium sulfate, nitric acid, chlorhydric acid, calcium chloride.Calcium chloride is preferred. The amount of coagulants depends on thetype of the used coagulant. Amounts in the range from 0.001% to 30% byweight with respect to the total amount of water in the reaction medium,preferably in the range from 0.01% to 5% by weight, can be used. Theintroduction of the polymer (C) at the beginning and/or during thepolymer (A) synthesis is preferred.

The latex of polymer (C) can be obtained by emulsion (or microemulsion)polymerization (with the involvement of a water soluble initiator) ormicrosuspension polymerization (with the involvement of an oil solubleinitiator). Processes comprising a microemulsion polymerization step asdescribed in U.S. Pat. No. 6,297,334 are suitable for preparing primaryparticles having a mean diameter of below 100 nm.

The latex of polymer (C) is preferably obtained by any processcomprising an emulsion or microemulsion polymerization step.

A detailed description of processes comprising an emulsionpolymerization step of fluorinated monomers is available notably in U.S.Pat. Nos. 4,016,345, 4,725,644 and 6,479,591.

During emulsion and/or microemulsion polymerization for obtainingpolymer (C), a mild stirring is advantageously applied to prevent thecoagulation of the perfluoropolymer primary particles.

The polymer (C) polymerization step takes place advantageously in thepresence of an emulsifier, preferably in a sufficiently high amount tostabilize the emulsion of the perfluoropolymer primary particles.

The emulsifier is preferably a fluorosurfactant. The fluorinatedsurfactants of formula:R_(f′)(X⁻)_(j)(M⁺)_(j)are the most commonly used, wherein R_(f′) is a (per)fluoroalkyl chainC₅-C₁₆ or a (per)fluoropolyoxyalkylene chain, X⁻ is —COO⁻ or —SO₃ ⁻, M⁺is selected from H⁺, NH₄ ⁺, an alkaline metal ion and j can be 1 or 2.As non limitative example of fluorinated surfactants mention may be madeof ammonium and/or sodium perfluorooctanoate,(per)fluoropolyoxyalkylenes having one or more carboxylic end groups.

More preferably, the fluorosurfactant is chosen from:

-   -   CF₃(CF₂)_(n1)COOM′, in which n₁ is an integer ranging from 4 to        10, preferably from 5 to 7, and more preferably being equal to        6; M′ represents H, NH₄, Na, Li or K, preferably NH₄;    -   T(C₃F₆O)_(n0)(CFXO)_(m0)CF₂COOM″, in which T represents Cl or a        perfluoroalkoxide group C_(k)F_(2k+1)O with k=integer from 1 to        3, one F atom being optionally substituted by a Cl atom; n₀ is        an integer ranging from 1 to 6; m₀ is an integer ranging from 0        to 6; M″ represents H, NH₄, Na, Li or K; X represents F or CF₃;    -   F—(CF₂—CF₂)_(n2)—CH₂ CH₂—SO₃M″′, in which M″′ represents H, NH₄,        Na, Li or K, preferably H; n₂ is an integer ranging from 2 to 5,        preferably n₂=3    -   A-R_(f)—B bifunctional fluorinated surfactants, in which A and        B, equal to or different from each other, are —(O)_(p)CFX—COOM*;        M* represents H, NH₄, Na, Li or K, preferably M* represents NH₄;        X═F or CF₃; p is an integer equal to 0 or 1; R_(f) is a linear        or branched perfluoroalkyl chain, or a (per)fluoropolyether        chain such that the number average molecular weight of A-R_(f)—B        is in the range 300-1,800.

A co-stabilizer is advantageously used in combination with theemulsifier. Paraffins with a softening point in the range 48° C.-62° C.are preferred as co-stabilizers.

The water-soluble initiator is advantageously chosen from persulphates,permanganates and hydrosoluble organic peroxides, such as disuccinicacid peroxide.

The water-soluble initiator can be optionally used in combination with areducing agent. An example thereof is (NH₄)₂Fe(SO₄)₂.6H₂O (Mohr's salt).

The latex of the polymer (C) can be used directly as obtained from theemulsion polymerization for the preparation of the composition accordingto the invention. In this case, the latex has a solid content usuallyranging from 20 to 30% wt.

Optionally, subsequent to the polymerization step, the latex of polymer(C) can be concentrated to increase the polymer (C) content up to atmost 65% wt. The concentrated latex can be notably obtained with anyoneof the processes known in the art. As an example, the concentrated latexcan be notably obtained by the addition of a nonionic surfactant and byheating above the cloud point of the above-mentioned nonionic surfactantand separating the supernatant water phase from the polymer-rich phase.Otherwise, the concentrated latex can be obtained by an ultrafiltrationmethod, well-known to those skilled in the art.

Optionally, the latex of polymer (C), either as obtained from thepolymerization step, or after a concentrating step as described above,can be further purified from the residues of anionic fluorinatedsurfactants used for the emulsion polymerization. In this case, latex ofpolymer (C) substantially free of anionic fluorinated surfactants isadvantageously obtained.

The step of preparing the thermoplastic halopolymer (A) isadvantageously carried out according to known techniques, bycopolymerization of the corresponding monomers, in suspension in organicmedium or in aqueous emulsion, in the present of a suitable radicalinitiator, at a temperature comprised between −60° and 150° C.,preferably between −20° C. and 100° C., more preferably between 0° and80° C. The reaction pressure is comprised between 0.5 and 180 bar,preferably between 5 and 140 bar.

Shall the thermoplastic halopolymer be a copolymer, the addition of thecomonomer(s) is carried out according to known techniques of the art;however a continuous or step by step addition of the comonomer(s) duringthe reaction is preferred.

Among the various radical initiators, it can be used in particular:

-   (i) bis-acylperoxides of formula (R_(f)—CO—O)₂, wherein R_(f) is a    (per)haloalkyl C₁-C₁₀ (see for instance EP 185 242 and U.S. Pat. No.    4,513,129), or a perfluoropolyoxyalkylene group (see for instance EP    186 215 and U.S. Pat. No. 5,021,516); among them,    bis-trichloroacetylperoxide and bis-dichlorofluoro acetylperoxide    are particularly preferred (see U.S. Pat. No. 5,569,728);-   (ii) dialkylperoxides of formula (RH—O)₂, wherein RH is an alkyl    C₁-C₁₀; diterbutylperoxide (DTBP) is particularly preferred;-   (iii) water soluble inorganic peroxides, such as ammonium or    alkaline metals persulphates or perphosphates; sodium and potassium    persulphate is particularly preferred;-   (iv) dialkylperoxydicarbonates, wherein the alkyl has from 1 to 8    carbon atoms, such as di-n-propyl-peroxydicarbonate and    di-isopropyl-peroxydicarbonate (see EP 526,216);-   (v) alkyl peroxyesters, like tert-amylperoxypivalate and    tert-butylperoxyisobutirate;-   (vi) organic or inorganic redox systems, such as ammonium    persulphate/sodium sulphite, hydrogen    peroxide/aminoiminomethansulphinic acid,    terbutylhydroperoxide/metabisulphite (see U.S. Pat. No. 5,453,477).

In the case of the suspension copolymerization, the reaction medium isnotably formed by an organic phase, to which water is usually added inorder to favor the heat dispersion developing during the reaction. Theorganic phase can be formed by the monomer(s) themselves, withoutaddition of solvents, or by the monomer(s) dissolved in a suitableorganic solvent. As organic solvents chlorofluorocarbons are commonlyused, such as CCl₂F₂ (CFC-12), CCl₃F (CFC-11), CCl₂F—CClF₂, (CFC-113),CClF₂—CClF₂ (CFC-114), and the like.

Since such products have a destroying effect on the ozone present in thestratosphere, alternative products have been recently proposed, such asthe compounds containing only carbon, fluorine, hydrogen and optionallyoxygen, described in U.S. Pat. No. 5,182,342. In particular(per)fluoropolyethers with at least one hydrogenated end group,preferably two, such as —CF₂H, —CF₂—CF₂H, —CF(CF₃)H, can be used. Avalid alternative is given by the hydrocarbons with branched chaindescribed in U.S. Pat. No. 5,434,229, having from 6 to 25 carbon atomsand a ratio between methyl groups and carbon atom number higher than0.5, such as for instance 2,3-dimethylbutane, 2,3-dimethylpentane,2,2,4-trimethylpentane, 2,2,4,6,6-pentamethylheptane,2,2,4,4,6-pentamethylheptane, etc, or mixtures thereof.

In the case of aqueous emulsion (co)polymerization, processes asdescribed above for emulsion and microemulsion polymerization of polymer(C) are also advantageously applied for the preparation of polymer (A).

The control of molecular weight of the thermoplastic halopolymer (A)generally needs the use of telogen agents (chain transfer agents) inpolymerization, owing to the fact that the used monomers generally donot show a telogen activity comparable to that of the known chaintransfer agents.

When chain transfer agents are used, these can be for examplehydrocarbons, alcohols, dialkylcarbonates, ketones, ethers, particularlymethyl-tert-butylether, or halogenated hydrocarbons, having from 1 to 6carbon atoms. Among them, chloroform, ethers, dialkylcarbonates andsubstituted alkyl cyclopentanes, such as methylcyclopentane areparticularly preferred (see U.S. Pat. No. 5,510,435). The transfer agentis introduced into the reactor at the beginning of the reaction, orcontinuously or step by step during the polymerization. The amount ofchain transfer agent can range within rather wide limits, depending onthe polymerization conditions (reaction temperature, monomers, molecularweight required of the polymer, etc). In general such amount ranges from0.01 to 30% by weight, preferably from 0.05 to 10% by weight, based onthe total amount of monomers introduced in the reactor.

The thermoplastic halopolymer composition of the invention can beprocessed following standard methods for injection molding, extrusion,thermoforming, machining, and blow molding.

Still an object of the invention is an article comprising thethermoplastic halopolymer composition as above described or obtainableby the process as above described.

Advantageously the article is an injection molded article, an extrusionmolded article, a machined article, a coated article or a castedarticle.

Non-limitative examples of articles are shaped article, pipes, fittings,housings, films, membranes, coatings.

Preferably the article is a pipe. Pipes according to the inventionadvantageously comprise at least one layer comprising the thermoplastichalopolymer composition.

Articles of the invention can advantageously find application in the oiland gas industry. Articles for oil field applications include shocktubing, encapsulated injection tubing, coated rod, coated controlcables, down-hole cables, flexible flow lines and risers.

A particular example of articles of the invention is provided byreinforced flexible pipes, notably used in the oil industry for thetransport of recovered fluids between installations at an oil field, andfor the transport of process liquids between an installation positionedat the surface of the sea and an installation positioned below thesurface of the sea. The reinforced flexible pipe of the inventiontypically comprises at least one layer comprising, preferably consistingessentially of the composition of the invention. It is also understoodthat the reinforced flexible pipe of the invention may comprise one ormore that one layer comprising (preferably consisting essentially of)the composition of the invention.

A common type of the above-mentioned reinforced flexible pipes hasgenerally a tight inner barrier layer comprising the composition of theinvention, on whose inner side a collapse resistant layer, frequentlycalled a carcass, is arranged, the purpose of which is to prevent theinner barrier layer from collapsing because of external pressureimpacts.

One or more load-carrying reinforcement layers are arranged externallyon the inner collapse resistant layer and the inner liner. Theseload-carrying reinforcement layers are sometimes also referred to aspressure reinforcement layers, tension reinforcement layers or crossreinforcement layers. These layers will be called hereinafter “the outerreinforcement layer”. Generally, the outer reinforcement layer iscomposed of two layers arranged on top of each other, where the layerclosest to the inner liner is of a nature such that it absorbs radialforces in the pipe (pressure reinforcement layer), while the overlyingreinforcement layer primarily absorbs axial forces in the pipe (tensionreinforcement layer). Finally, the outer reinforcement layer may havearranged externally thereon a tight jacket or external fluid barrier,which avoid the outer reinforcement layer to be freely exposed to thesurroundings and which assure thermal insulation. Also, said externalfluid barrier may comprise the composition of the invention.

Articles of the invention are also particularly suitable for the CPImarket, that is to say for the so-called chemical process industry,wherein, typically:

-   -   corrosion-resistant linings comprising the composition of the        invention can be applied by powder coating, sheet lining,        extruded lining, rotational lining or other standard technique;    -   membranes comprising the composition of the invention can be        made with varying degrees of porosity and manufacturing methods        for use in water purification, foodstuffs dehydration,        filtration of chemicals, and the like;    -   pipes, valves, pumps and fittings comprising the composition as        above described can be used in chemical process equipment when        excellent temperature and chemical resistance are required.        Small pieces can economically be made entirely of the        composition of the invention. Extruded or molded components        include tubes, pipes, hose, column packing, pumps, valves,        fittings, gaskets, and expansion joints.

Also, articles of the invention are advantageously suitable for buildingand architecture applications; in this domain, typically:

-   -   flexible corrugated ducts comprising the composition of the        invention advantageously prevent corrosion from SO₂ and other        products of combustion in residential chimney flues;    -   pipes and fittings comprising the composition of the invention        advantageously provide for long life hot water service.

Moreover, articles of the invention can advantageously find applicationin the semiconductors industry, where the composition of the inventioncan, for instance, act as strong, tough, high purity material usedroutinely as structural materials in wet bench and wafer processingequipment. Moreover, the composition of the invention is suitable forconstruction of fire-safe wet benches and for windows, access panels,mini-environments, site glasses, and any other area within the cleanroomwhere transparency is needed.

The addition of a (per)fluoropolyether (B) and of aper(halo)fluoropolymer (C) advantageously enables improvement ofrheological behavior of thermoplastic halopolymer (A), making possibleprocessing in less severe conditions and yielding final parts withoutstanding surface aspect and good homogeneity and coherency.

The process according to the invention is advantageously particularlyefficient in assuring optimal distribution of the (per)fluoropolyether(B) and of the per(halo)fluoropolymer (C) in the thermoplastichalopolymer composition, which enables increased efficiency of polymers(B) and (C) as processing aids and avoids negative impact on mechanicalproperties.

Some examples of the present invention are reported hereinafter, whosepurpose is merely illustrative but not limitative of the scope of theinvention itself.

EXAMPLES

Analytical Methods

SEM Microscopy

SEM microscopy pictures have been taken using the electronic scanningmicroscope (SEM) model Stereoscan 200 by Cambridge Instruments atdifferent magnification levels (from 32 to 10 000×) either on samplefractured at liquid nitrogen temperature, or on final shaped articles.

Dynamic Viscosity

Dynamic viscosity of the polymer is measured at a shear rate of 1 s⁻¹and at a temperature exceeding of roughly 30° C. the melting point ofsaid polymer with a Rheometric Scientific ARES controlled strainrheometer, employing an actuator to apply a deforming strain to thesample and a separate transducer to measure the resultant stressdeveloped within the sample, and using the parallel plate fixture.

TFE/HFP Polymer Composition

The HFP content for the TFE/HFP copolymers is determined by measuringthe IR absorbance at 982 cm⁻¹ (A_(982 cm) ⁻¹ ) and at 2367 cm⁻¹(A_(2367 cm) ⁻¹ ) on a 50 μm-thick compression molded film. HFP contentis calculated according to the following formula:

${HFP}_{({\%\mspace{14mu}{wt}})} = {\frac{\alpha_{982\mspace{14mu}{cm}^{- 1}}}{\alpha_{2367\mspace{14mu}{cm}^{- 1}}} \times 3.2}$${HFP}_{({\%\mspace{14mu}{moles}})} = {\frac{\left( {100 \times {HFP}_{({\%\mspace{14mu}{wt}})}} \right)}{\left( {150 - {0.5 \times {HFP}_{({\%\mspace{14mu}{wt}})}}} \right)} \times 3.2}$Polymer Latex Particle Size

The average particle size of the polymer latex has been measured by thedynamic laser light scattering (DLLS) technique according to the methoddescribed in B. Chu “Laser light scattering” Academic Press, New York(1974), using a Brookhaven Scientific Instrument, composed by the BI9000correlator and by the BI200SM goniometer. The used light source is anargon ion laser Spectra Physics (wave length 514.5 nm).

Differential Scanning Calorimetry

DSC measurements have been performed at a heating rate of 10° C./min,according to ASTM D 3418.

Comparative Example 1

Melt compounding and pipe extrusion of a composition of a thermoplasticfluoropolymer and a (per)fluoropolyether

A blend comprising a mixture of SOLEF® 6015 and SOLEF® 31515 VdFpolymers (67/33 wt/wt) and 0.1% by weight of a fluoropolyether complyingwith the following formula:HO—CH₂CF₂O—(CF₂O)_(q)(CF₂CF₂O)_(p)—CF₂CH₂—OHwhose main physico-chemical properties are listed here below:

M_(w) (amu) 2000 Difunctional content (NMR) (%) 94 p/q ratio (NMR) ~1Kinematic viscosity (cSt) 85 Density at 20° C. (g/cm³) 1.81 Vaporpressure @ 100° C. (torr) 2 × 10⁻⁵ Surface tension @ 20° C. (dyne/cm) 24were mixed for 5 hours in a rotary blender and melt compounded in aBraebender conical twin-screw Hastelloy C-276 extruder having a finaldiameter of 18 mm. Temperature profile and extrusion parameters aredetailed in Table 1.

TABLE 1 Zone 1 temperature (hopper) (° C.) 200 Zone 2 temperature(barrel) (° C.) 210 Zone 3 temperature (barrel) (° C.) 220 Zone 4temperature (head) (° C.) 230 Torque (Nm) 36 Pressure (bar) 67 Melttemperature (° C.) 231 Throughput rate (kg/h) 3.6 Screw speed (rpm) 15

The composition was then extruded to manufacture pipes having anexternal diameter of 25 mm and a thickness of about 2-3 mm. Pipeextrusion was carried out in a single screw extruder with a diameter of45 mm. The diameter of the die was 53.7 mm and the diameter of the tipwas 43.6 mm. The temperature profile and extrusion parameters arereported in the following table 2 for two different screw speeds.

TABLE 2 Zone 1 temperature (barrel) (° C.) 190 190 Zone 2 temperature(barrel) (° C.) 200 200 Zone 3 temperature (barrel) (° C.) 210 210 Zone4 temperature (barrel) (° C.) 210 210 Zone 5 temperature (neck) (° C.)215 215 Zone 6 temperature (neck) (° C.) 210 210 Zone 7 temperature(body) (° C.) 215 215 Zone 8 temperature (die holder) (° C.) 210 210Zone 8 temperature (die) (° C.) 220 220 Head pressure (bar) 28 35 Melttemperature (° C.) 257 257 Screw speed (rpm) 15 40 Extruder consumption(A) 30 30 Extruder Voltage (V) 51 51 Output Kg/h 8.3 17.8

The extruded pipe has a smooth surface, with no visible crack and/orsurface defect.

Mechanical properties were evaluated on specimens from the extruded pipeand measured according to ASTM D 638.

Results are detailed in Table 3.

TABLE 3 Stress Strain Stress Strain Thermoplastic (per)fluoropolyetherElastic at at at at fluoropolymer (B) modulus yield yield breack breack(A) Nature Amount (MPa) (MPa) (%) (MPa) (%) SOLEF ® 6015 See above 0.1%by 945 33.3 12.2 55.6 372 PVDF + SOLEF ® weight of 31515 PVDF (A) (67/33wt/wt)

Comparative Example 2

Melt Compounding and Pipe Extrusion of a Composition of a ThermoplasticFluoropolymer

A blend of SOLEF® 6015 and SOLEF® 31515 VdF polymers (67/33 wt/wt) hasbeen dry mixed for 5 hours in a rotary blender and melt compounded in aBraebender conical twin-screw extruder as described in comparativeexample 1.

The thus obtained blend has a MFI (230° C./10 kg) of 0.5 g/10 min.

The blend was then extruded to make tubes with an external diameter of25 mm and a thickness of about 2-3 mm, as described in comparativeexample 1. Details of pipe extrusion parameters, at two different screwspeeds, are detailed in Table 6.

TABLE 4 Zone 1 temperature (barrel) (° C.) 190 190 Zone 2 temperature(barrel) (° C.) 210 210 Zone 3 temperature (barrel) (° C.) 210 210 Zone4 temperature (barrel) (° C.) 210 210 Zone 5 temperature (neck) (° C.)215 215 Zone 6 temperature (neck) (° C.) 210 210 Zone 7 temperature(body) (° C.) 215 215 Zone 8 temperature (die holder) (° C.) 210 210Zone 8 temperature (die) (° C.) 220 220 Head pressure (bar) 33 41 Melttemperature (° C.) 254 256 Screw speed (rpm) 15 25 Extruder consumption(A) 34 38 Extruder Voltage (V) 51 79

The pipes extruded in either condition had surface defects, like visiblecracks on its surface.

Evaluation of mechanical properties on such extruded material was thusimpossible.

Example 3 Example 3a

Preparation of a Melt-Processible Perfluoropolymer

A 5 l AISI 316 autoclave equipped with a stirrer working at 650 rpm wasevacuated and there were introduced 3 l of demineralized water and 22.5g of a microemulsion formed of:

-   -   20% by weight of GALDEN® D02, having the formula:        CF₃O—(CF₂CF(CF₃)O)_(m)(CF₂O)_(n)—CF₃    -   where m/n=20 and average molecular weight of 450;    -   40% by weight of a surfactant having the formula:        Cl—(C₃F₆O)—(CF₂CF(CF₃)O)_(m1)—(CF(CF₃)O)_(q)—(CF₂O)_(n1)—CF₂COO⁻K⁺    -   where n₁=0.8% m₁, q=9.2% m₁ and average molecular weight of 540;    -   the remaining part being formed by H₂O.

The autoclave was heated to the reaction temperature of 85° C. and HFPwas then introduced to bring the total pressure in the vessel to 13.50absolute bar. Then ethane was charged as chain transfer agent until thetotal pressure reached 13.60 absolute bar, and afterwards a TFE/HFPmixture containing 10% by moles of HFP was fed to obtain the reactionpressure of 21 absolute bar.

The polymerization was initiated by introducing 150 ml of a potassiumpersulfate (KPS) solution, obtained by dissolving 30 g KPS in 1 liter ofdemineralized water.

The reaction pressure was kept constant by feeding the monomer mixtureTFE/HFP containing 10% by moles of HFP. At 60 and 120 minutes from thereaction start, 75 ml of KPS solution were fed. After 161 minutes ofreaction, the polymerization was stopped, cooling the reactor to roomtemperature and releasing the residual pressure.

A latex containing 202 (g polymer)/(kg latex) was discharged (averageprimary particles size=125 nm) and coagulated with HNO₃, then thepolymer was separated, washed with demineralized water and dried in anoven at 175° C. for about 16 hours.

The obtained powder has a dynamic viscosity of 210 Pa×s at 250° C. andat a shear rate of 1 sec⁻¹, a T_(m2) of 220° C., a ΔH_(2f)=18.9 J/g andis composed of 12% by moles of HFP and 88% by moles of TFE.

Example 3b

Melt Compounding and Pipe Extrusion of a Composition of a ThermoplasticFluoropolymer, a (Per)Fluoropolyether and a Melt-ProcessiblePerfluoropolymer

A blend comprising a mixture of SOLEF® 6015 and SOLEF® 31515 VdFpolymers (67/33 wt/wt), 0.1% of the (per)fluoropolyether of comparativeexample 1 and 1% by weight of the TFE/HFP copolymer of example 3a) weredry mixed for 5 hours in a rotary blender and melt compounded in aBraebender conical twin-screw Hastelloy C-276 extruder having a finaldiameter of 18 mm.

SOLEF® 6015 and SOLEF® 31515 VdF polymers are respectively a VdFhomopolymer and a VdF/CTFE copolymer, commercially available from SolvaySolexis S.p.A.

Temperature profile and extrusion parameters are detailed in Table 5.

TABLE 5 Zone 1 temperature (hopper) (° C.) 200 Zone 2 temperature(barrel) (° C.) 210 Zone 3 temperature (barrel) (° C.) 220 Zone 4temperature (head) (° C.) 230 Torque (Nm) 45 Pressure (bar) 96 Melttemperature (° C.) 227 Throughput rate (kg/h) 4 Screw speed (rpm) 15

The composition was then extruded to manufacture pipes having anexternal diameter of 25 mm and a thickness of about 2-3 mm. They wereextruded in a single screw extruder with a diameter of 45 mm. Thediameter of the die was 53.7 mm and the diameter of the tip was 43.6 mm.The temperature profile and extrusion parameters are reported in thefollowing Table 6.

TABLE 6 Zone 1 temperature (barrel) (° C.) 190 Zone 2 temperature(barrel) (° C.) 200 Zone 3 temperature (barrel) (° C.) 210 Zone 4temperature (barrel) (° C.) 210 Zone 5 temperature (neck) (° C.) 215Zone 6 temperature (neck) (° C.) 210 Zone 7 temperature (body) (° C.)215 Zone 8 temperature (die holder) (° C.) 210 Zone 8 temperature (die)(° C.) 220 Head pressure (bar) 23 Melt temperature (° C.) 257 Screwspeed (rpm) 15 Extruder consumption (A) 33 Extruder Voltage (V) 51Output (Kg/h) 8.2

At a given throughput of roughly 8 kg/h, composition of example 3bcomprising a melt processible perfluoropolymer has shown a lower headpressure (23 bar) than a similar composition free from polymer (C) (seecomparative example 1, table 2; pressure head of 28 bar at 8.3 kg/h ofthroughput).

The extruded pipe had a smooth surface, with no visible crack and/orsurface defects. Mechanical properties have been evaluated on specimensusined from extruded pipes and measured according to ASTM D 638. Resultsare detailed in Table 6.

TABLE 6 melt-processible Stress Strain Stress Strain Thermoplastic(per)fluoropolyether perfluoropolymer Elastic at at at at fluoropolymer(B) (C) modulus yield yield breack breack (A) nature Amount Natureamount (MPa) (MPa) (%) (MPa) (%) SOLEF ® 6015 See 0.1% by From 1.0% 93932.6 12.4 59.5 421 PVDF + SOLEF ® example weight of example 31515 PVDF 1(A) 2a) (67/33 wt/wt)

FIG. 1 is a SEM picture (magnification: 10 000×) of a specimen sampledfrom an extruded pipe of the thermoplastic composition of example 3b,after fragile rupture at liquid nitrogen temperature. White spots arephase separated domains of melt-processible perfluoropolymer (C).

Example 4

Preparation of a Melt-Processible Perfluoropolymer

A 22 l AISI 316 autoclave equipped with a stirrer working at 500 rpm wasevacuated and there were introduced 14.5 l of demineralized water and127 g of a microemulsion formed of:

20% by weight of GALDEN® D02, having the formula:CF₃O—(CF₂CF(CF₃)O)_(m)(CF₂O)_(n)—CF₃where m/n=20 and average molecular weight of 450;30% by weight of a surfactant having the formula:Cl—(C₃F₆O)—(CF₂CF(CF₃)O)_(m1)—(CF(CF₃)O)_(q)—(CF₂O)_(n1)—CF₂COO⁻NH₄ ⁺where n1=1.0% m1, q=9.1% m1 and average molecular weight of 550; theremaining part being formed by H₂O.

The autoclave was put to vacuum and then heated to the reactiontemperature of 75° C. Then ethane was charged as chain transfer agentwith a delta pressure of 2.0 bar, perfluoromethoxyvinylether (PMVE) wascharged with a delta pressure of 6.3 bar, and afterwards a TFE/PMVEmixture containing 13% by moles of PMVE was fed to obtain the reactionpressure of 21 absolute Bar.

The polymerization was initiated by introducing 315 ml of a ammoniumpersulfate (APS) solution, obtained by dissolving 14.5 g APS in 1 literof demineralized water.

The reaction pressure was kept constant by feeding the monomer mixtureTFE/PMVE containing 13% by moles of PMVE. After 290 minutes of reaction,the polymerization was stopped, cooling the reactor to room temperatureand releasing the residual pressure.

A latex containing 329 (g polymer)/(kg latex) was discharged andcoagulated with HNO₃, then the polymer was separated, washed withdemineralized water and dried in an oven at 120° C. for about 16 hours.

The obtained powder has a dynamic viscosity of 5 Pa×s at 280° C. and ata shear rate of 1 s⁻¹, a T_(m2) of 205.9° C., a ΔH_(2f)=6.279 J/g and iscomposed of 13% by moles of PMVE and 87% by moles of TFE.

Example 5

Melt Compounding and Tape Extrusion of a Composition of a ThermoplasticFluoropolymer, a Melt-Processable Fluoropolymer, and a(Per)Fluoropolyether

A blend comprising a mixture of SOLEF® 6015 and SOLEF® 21216 VdFpolymers (55/45 wt/wt), 1% by weight of the TFE/PMVE copolymer ofexample 12 and 0.3% by weight of a fluoropolyether complying with thefollowing formula:HO—CH₂CF₂O—(CF₂O)_(q)(CF₂CF₂O)_(p)—CF₂CH₂—OHwhose main physico-chemical properties are listed here below:

M_(w) (amu) 2000 Difunctional content (NMR) (%) 94 p/q ratio (NMR) ~1Kinematic viscosity (cSt) 85 Density at 20° C. (g/cm³) 1.81 Vaporpressure @ 100° C. (torr) 2 × 10⁻⁵ Surface tension @ 20° C. (dyne/cm) 24were mixed for 5 hours in a rotary blender and melt compounded in aBraebender conical twin-screw Hastelloy C-276 extruder having a finaldiameter of 18 mm. SOLEF® 6015 and SOLEF® 21216 VdF polymers arerespectively a VdF homopolymer and a VdF/HFP copolymer, commerciallyavailable from Solvay Solexis S.p.A., having a MFI of roughly 0.2 g/10min (230° C./5 kg). Temperature profile and extrusion parameters aredetailed in Table 7.

TABLE 7 Zone 1 temperature (hopper) (° C.) 200 Zone 2 temperature(barrel) (° C.) 210 Zone 3 temperature (barrel) (° C.) 220 Zone 4temperature (head) (° C.) 230 Torque (Nm) 43 Pressure (bar) 55 Melttemperature (° C.) 231 Throughput rate (kg/h) 4.2 Screw speed (rpm) 15

The composition was then extruded to manufacture tapes of about 6 mmnominal thickness in the same extruder as above explained, equipped withan extruder head of 10 mm. The temperature profile and extrusionparameters are reported in the following Table 8.

TABLE 8 Temp. 1 (° C.) 200 Temp. 2 (° C.) 210 Temp. 3 (° C.) 220 Temp. 4(° C.) 230 Vacuum No rpm 3 Pressure (bar) 0.2 (transducer calibrate at−0.7 bar) Torque (Nm) 15 Output (kg/h) 0.58 Sheet drawing speed (m/min)0.1-0.2 Sheet thickness (μm) between 6200 and 6500 Rolls Temp (° C.) 140

Speciments were machined out of the extruded tapes and submitted toT_(db) measurement. The T_(db) value obtained was 15° C.

Mechanical properties were evaluated on specimens of 0.4 mm obtained bycompression moulding of the tapes above prepared and measured accordingto ASTM D 638.

Results are detailed in Table 9.

TABLE 9 melt-processible Stress Strain Stress Strain Thermoplastic(per)fluoropolyether perfluoropolymer Elastic at at at at fluoropolymer(B) (C) modulus yield yield breack breack (A) nature Amount Natureamount (MPa) (MPa) (%) (MPa) (%) SOLEF ® 6015 See 0.3% by From 1.0% 97036 9 66.3 466 PVDF + SOLEF ® above weight of example 21216 PVDF (A) 4(55/45 wt/wt)

Example 6

Melt Compounding and Tape Extrusion of a Composition of a ThermoplasticFluoropolymer, a Melt-Processable Fluoropolymer, a (Per)Fluoropolyetherand a Plasticizer

Example 5 was repeated except that to the composition was added 2.5%weight of dibutylsebacate (DBS) (based on weight of thermoplasticfluoropolymer (A)). The thermoplastic composition was then extruded intopellets which were used for the manufacture of tapes of about 6 mmthickness. The temperature profile and extrusion parameters are reportedin the following Table 10.

TABLE 10 Temp. 1 (° C.) 200 Temp. 2 (° C.) 210 Temp. 3 (° C.) 220 Temp.4 (° C.) 230 Vacuum No rpm 4 Pressure (bar) 0.5 Torque (Nm) 11.3 Output(kg/h) 0.69 Sheet drawing speed (m/min) 0.2 Sheet thickness (μm) c.a.6200 Rolls Temp (° C.) 140

Specimens were machined out of the extruded tapes and submitted toT_(db) measurement. The T_(db) value obtained was −10° C.

Mechanical properties were evaluated on specimens of 0.4 mm obtained bycompression moulding from the tapes above prepared and measuredaccording to ASTM D 638.

Results are detailed in Table 11.

TABLE 11 melt-processible Stress Strain Strain Plasti- Thermoplastic(per)fluoropolyether perfluoropolymer Elastic at at Stress at cizer,fluoropolymer (B) (C) modulus yield yield at breack DBS (A) natureAmount Nature amount (MPa) (MPa) (%) breack (MPa) (%) SOLEF ® 6015 See0.3% by From 1.0% 820 31.9 13.9 70.9 513 2.5 PVDF + SOLEF ® above weightof example 21216 PVDF (A) 4 (55/45 wt/wt)

It appears clearly from the above example that the compositioncontaining the plasticizer has a lower T_(db) and a high strain at yieldrespect to the composition without plasticizer. Both features areespecially appreciated when the compositions are used for themanufacture of articles for oil and gas applications, in particularoff-shore tubes and pipes.

1. Thermoplastic halopolymer composition comprising: thermoplastichalopolymer, polymer (A), comprising: a mixture of: from 25% to 55% byweight of polymer (A) of at least one vinylidenefluoride (VdF)homopolymer, and from 45% to 75% by weight of polymer (A) of at leastone VdF copolymer comprising from 0.1% to 15% by moles of a fluorinatedcomonomer selected from the group consisting of vinylfluoride (VF₁),chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP),tetrafluoroethylene (TFE), trifluoroethylene (TrFE), and mixturesthereof; from 0.01 to 5% by weight of polymer (A) of at least one(per)fluoropolyether, polymer (B); and from 0.3 to 10% by weight ofpolymer (A) of at least one per(halo)fluoropolymer, polymer (C).
 2. Thecomposition according to claim 1, wherein the (per)fluoropolyethercomprises recurring units (R1) selected from the group consisting of:(I) —CFX—O—, wherein X is —F or —CF₃; and (II) —CF₂—CFX—O—, wherein X is—F or —CF₃; and (III) —CF₂—CF₂—CF₂—O—; and (IV) —CF₂—CF₂—CF₂—CF₂—O—; and(V) —(CF₂)_(j)—CFZ—0— wherein j is an integer from 0 to 3 and Z is afluoropolyoxyalkene chain comprising from 1 to 20 recurring units chosenamong the classes (I) to (IV) here above; and mixtures thereof.
 3. Thecomposition according to claim 2, wherein the (per) fluoropolyether is acompound complying with formula (I) here below:Ti—(CFX)_(p)—O—R_(f)—(CFX)_(p′)-T₂  (I) wherein: each of X isindependently F or CF₃; p and p′, equal or different each other, areintegers from 0 to 3; R_(f) is a fluoropolyoxyalkene chain comprisingrepeating units R^(o), said repeating units being chosen among the groupconsisting of: (i) —CFXO—, wherein X is F or CF₃, (ii) —CF₂CFXO—,wherein X is F or CF₃, (iii) —CF₂CF₂CF₂O—, (iv) —CF₂CF₂CF₂CF₂O—, (v)—(CF₂)_(j)—CFZ-0- wherein j is an integer chosen from 0 and 1 and Z is agroup of general formula -0R_(f)T₃, wherein R_(f)′ is afluoropolyoxyalkene chain comprising a number of repeating units from 0to 10, said recurring units being selected from the group consisting of-—CFXO—, —CF₂CFXO—, —CF₂CF₂CF₂ 0-, —CF₂CF₂CF₂CF₂O—, with each of X beingindependently F or CF₃; and T₃ is a C₁-C₃ perfluoroalkyl group, andmixtures thereof; T₁ and T₂, the same or different each other, are H,halogen atoms, C₁-C₃₀ end-group optionally comprising heteroatoms chosenamong 0, S, N, and/or halogen atoms.
 4. The composition according toclaim 3, wherein the (per)fluoropolyether (B) is selected from the groupconsisting of: (a) HO—CH₂CF₂0(CF₂0)_(n′)(CF₂CF₂0)_(m′)CF₂CH₂-0H, m′ andn′ being integers, where the ratio m′/n′ ranges between 0.1 and 10; (b)HO(CH₂CH₂0)_(n)CH₂CF₂0(CF₂0)_(n′)(CF₂CF₂0)_(m′)OH F₂CH₂(OCH₂CH₂)_(n)0H,m′ and n′ being integers, where the ratio m′/n′ ranges between 0.1 and10, and n ranges between 1 and 3; (c) HCF₂O(CF₂O)_(n)(CF₂CF₂0)_(m′)CF2H, m′ and n′ being integers, where the ratio m′/n′ranges between 0.1 and 10; (d) FCF₂0(CF₂0)_(n′)(CF₂CF₂0)_(m′)CF₂F, m′and n′ being integers, where the ratio m′/n′ generally ranges between0.1 and
 10. 5. Process for manufacturing the thermoplastic halopolymercomposition according to claim 1, said process comprising mixing: (i)the thermoplastic halopolymer (A); (ii) the (per)fluoropolyether (B);(iii) the per(halo)fluoropolymer (C); and (iv) optionally, otheradditives or filling materials.
 6. The process according to claim 5,said process comprising mixing by dry blending and/or melt compoundingpolymer (A), polymer (B) and polymer (C).
 7. The process according toclaim 6, said process comprising mixing the polymer (A) and the polymer(C) in the form of latexes.
 8. The process according to claim 6, saidprocess further comprising the step of mixing by synthesizing polymer(A) in the presence of polymer (C).
 9. The process according to claim 5,said process comprising mixing polymer (C) in the form of particleshaving an average primary particle size of less than 300 nm.
 10. Articlecomprising the thermoplastic halopolymer composition obtained by theprocess of claim
 5. 11. Article comprising the thermoplastic halopolymercomposition according to claim
 1. 12. The composition according to claim1, wherein the polymer (C) is selected from the group consisting ofnon-fibrillating PTFE and TFE copolymers comprising at least 2% wt, andat most 30% wt of recurring units derived from at least one fluorinatedcomonomer selected from the group consisting of: (i)perfluoroalkylvinylethers complying with formula CF₂═CFOR_(f1′), inwhich R_(f1′) is a C₁-C₆ perfluoroalkyl, e.g. CF₃, C₂F₅, C₃F₇; and/or(ii) perfluoro-oxyalkylvinylethers complying with formula CF₂═CFOX₀, inwhich X₀ is a C₁-C₁₂ perfluorooxyalkyl having one or more ether groups;and/or (iii) C₃-C₈ perfluoroolefins.
 13. The composition according toclaim 12, wherein the non-fibrillating PTFE has a number averagemolecular weight of below 1,000,000 and a melt viscosity of below 10⁴Pa·s, as measured at 372° C.